AI 中文总结
本文以MORFEO-HARMONI LGS波前传感器为案例，量化微透镜形状缺陷对ELT级望远镜LGS波前传感的影响，提出相关模型并经实验验证，结果可推广至GMT、TMT等大型望远镜的LGS系统。
AI 中文摘要
极大望远镜（ELT）上的激光导星（LGS）自适应光学（AO）系统依赖配备大画幅微透镜阵列的夏克-哈特曼波前传感器（SHWFS）。微透镜表面轮廓的制造缺陷会降低光斑质量并削弱质心定位精度，但在完整AO系统性能语境中，该效应很少被量化。本文以MORFEO-HARMONI LGS波前传感器设计为主要测试案例，全面表征微透镜形状对LGS波前传感的影响，所得结果可直接应用于GMT、TMT等ELT级或未来大型望远镜的LGS仪器。从原型微透镜的干涉表面轮廓测量出发，推导诱导的相位误差，并计算质心（CoG）光斑检测精度随LGS延展度和流量的退化情况：与理想透镜相比，实际微透镜使CoG方差降低1.8至2.4倍，相当于维持相同测量精度需约两倍的光子流量；该效应随LGS延展度增大而减弱，随微透镜矢高增加而改善。随后将每个子孔径的流量损失模型传播至层析AO端到端模拟，多颗LGS的测量冗余及最小均方误差（MMSE）重构器权重可部分缓解该惩罚，使有效斯特列尔比的流量损失降至1.25至1.4倍。通过LAM的LGS波前传感器光学台面原型提供实验验证，该原型还可单次测量实现全阵列表征。该方法广泛适用于任何低流量工况下的夏克-哈特曼系统。
英文摘要
Laser Guide Star (LGS) adaptive optics systems on extremely large telescopes (ELTs) rely on Shack-Hartmann wavefront sensors (SHWFS) equipped with large-format microlens arrays. Manufacturing imperfections in the microlens surface profile degrade spot quality and reduce centroiding accuracy, yet this effect is rarely quantified in the context of full AO system performance. This paper presents a comprehensive characterization of the impact of microlens shape on LGS wavefront sensing, using the MORFEO-HARMONI LGS wavefront sensor design as the primary test case, results are directly applicable to any ELT-class or future large-telescope LGS instrument, including systems on the GMT and TMT. Starting from interferometric surface profile measurements of prototype microlenses, we derive the induced phase errors and compute the degradation of center-of-gravity (CoG) spot detection accuracy as a function of LGS elongation and flux. A real microlens degrades CoG variance by a factor of 1.8 to 2.4 compared to an ideal lens, equivalent to requiring approximately twice the photon flux to maintain the same measurement accuracy. This effect is shown to decrease with increasing LGS elongation, and to improve with higher microlens sag. The per-subaperture flux-loss model is then propagated into tomographic AO end-to-end simulations, where measurement redundancy across multiple LGS and MMSE reconstructor weighting partially mitigate the penalty, reducing the effective Strehl ratio flux loss to factors of 1.25-1.4. Experimental validation is provided with the LGS wavefront sensor optical bench prototype at LAM, which also enables full-array characterization in a single measurement. The methodology is broadly applicable to any Shack-Hartmann system operating in a low-flux regime.
